This looks really nice , wondering does the threaded rod cut into the steel tape over time or do you use special tape already threaded?
Do you think it would be possible to use a softer material instead of steel to reduce vibration noise from the stepper motor ( like a teflon or hard plastic based material that is strong but soft). It could embed easily with tight tolerances.
I am interested in this method for my new wedge mount.
Malcolm, I might be wrong but I don't think the threaded rod contacts the steel tape. The rod turns inside the two nuts and that moves the carriage along, and the friction between the two pieces of steel tape drives the axis.
I made a sequence of three drawings showing the operation of the device.
The same works for traction and not by friction. The steel tape is pulled by doing so the disk spins. Thus there is no slippage, and while the device is well adjusted, the operation is very good. http://marcosbaun.multiply.com/photos/album/26#
I built a similar device about 18 years ago to drive an equatorial mount ( I never actually fitted it to the mount because I got a loan repaid and bought a LX200). The mount was made from parts salvaged from a land cruiser diff.
I used a cheap 3/8" threaded rod and the shuttle was made with two nuts welded to a piece of steel. I made thrust races for the rod (I have a lathe) and used a stepper motor salvaged from a HDD. I used a length of bowden cable in lieu of the steel tape running over a couple of pulleys at the ends of the worm assembly. I made drawings in ACAD at the time but I can't find them now. I actually made two devices one for the RA and one for the Dec. The actual cost for the project was $20 for the diff and a couple of $'s for the threaded rod. everything else was scrap.
I also wrote a program in Qbasic to drive the stepper motors and circuit board. (that's the only thing I have left of the project) with star and solar system objects, a two star alignment a facility and goto.
I had the whole drive mechanics operating on the bench but never actually used it. I was very interested to hear some one actually got one to work.
Malcolm, I might be wrong but I don't think the threaded rod contacts the steel tape. The rod turns inside the two nuts and that moves the carriage along, and the friction between the two pieces of steel tape drives the axis.
Adam
Hi Adam,
I managed to figure it out, there is 2 steel tapes one is connected to one side of the radius and the other connected to the other side on the wood. The other steel tape is connected in the reverse. It is quite ingenious actually as it would reduce noise transferred from the motor more than direct gears.
The piano wire method is only similar in concept, still may work though but I like the steel tape idea. You adjust the thickness of the steel tape depending on the weight you wish to load on the system.
A very good idea. A friend of mine used something similar : https://sites.google.com/a/astronomo...lesc%C3%B3pio2
One of the problems I see and also have in my project, is that if you want 360 degrees of rotation, the size of the threaded rod is very large (ie worse in my project). Anyway, in both projects, you can make 360 degrees, leave the size of the threade rod compatible with the size of the circumference of the disc
, wondering does the threaded rod cut into the steel tape over time or do you use special tape already threaded?
